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#ifndef EXOTICA_CORE_TASK_MAPS_LOOKAT_H_
#define EXOTICA_CORE_TASK_MAPS_LOOKAT_H_

#include <exotica_core/task_map.h>

#include <exotica_core_task_maps/look_at_initializer.h>

namespace exotica
{
/// \class LookAt
///
/// \ingroup TaskMap
///
/// \brief Points end-effector to look at a given target.
/// Looks at a target point by penalizing the vector which defines the orthogonal projection onto a defined line in the end-effector frame.
///
/// The task map relies on defining three frames for each target to be looked at:
///  - (0) the EffPoint in the end-effector frame (use in task map)
///  - (1) the LookAtTarget in the end-effector frame (use in task map)
///  - (2) the LookAtTarget in the world frame (use by user to easily return target in world coordinates - can be retrieved via get_look_at_target_in_world)
///
/// \image html taskmap_lookat.png "LookAt task map." width=500px
///
/// Given the point \f$p\f$ (the point to look at) defined in the end-effector space the task map is expressed by
/// \f[
///  \Phi = \vec{d}
/// \f]
/// where \f$\vec{d}:=p - a\f$ where \f$a\f$ is the orthogonal projection onto the line \f$L\f$ given by
/// \f[
///  L:=\{\alpha c : \alpha\in\mathbb{R}\}
/// \f]
/// and \f$c\f$ is some fixed point in the end-effector frame.
///
/// The LookAt task map can handle a goal for each end-effector. Three frames must be defined in the .xml for every goal.
class LookAt : public TaskMap, public Instantiable<LookAtInitializer>
{
public:
    LookAt();
    virtual ~LookAt();

    void Instantiate(LookAtInitializer& init) override;
    void Update(Eigen::VectorXdRefConst x, Eigen::VectorXdRef phi) override;
    void Update(Eigen::VectorXdRefConst x, Eigen::VectorXdRef phi, Eigen::MatrixXdRef jacobian) override;
    int TaskSpaceDim() override;

    Eigen::Vector3d get_look_at_target_in_world(const int& i);

private:
    int n_end_effs_;  ///< Number of end-effectors.
    int n_;           ///< Dimension of the task space.
};
}  // namespace exotica

#endif  // EXOTICA_CORE_TASK_MAPS_LOOKAT_H_
